Unable to use google/apis/annotations

I try to use REST over gRPC using google api annotations. Unfortunately, I'm facing a protoc issue telling me annotations.proto is not exists or had errors. I tried several fixes in vain.

I even tried to reinstall a complete stack in case I did something wrong. I will detail you as much as possible the full lines and files I have set from my fresh install.

From a fresh go install VM I type these shell lines :

$ mkdir sources/golang

$ echo 'export GOPATH=$HOME/sources/golang' >> $HOME/.zshrc

$ source ~/.zshrc

$ cd sources/golang

$ mkdir src

$ cd src

$ export PATH=$PATH:$GOPATH/bin

$ go get -u google.golang.org/grpc

$ go get -u github.com/golang/protobuf/protoc-gen-go

$ go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway

$ go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-swagger

$ mkdir -p test/proto/test

$ cd test/proto/test

$ vim test.proto

In My test.proto file, I wrote very basic lines :

syntax = "proto3";

package main;

import "google/api/annotations.proto";

service Tester {
    rpc Test (Request) returns (Reply) {
        option (google.api.http) = { get: "/v1/test" };
    }
}

message Request {
    string Message = 1;
}

message Reply {
    string Message = 1;
}

Then

$ cd $GOPATH/src

$ vim main.go

In my main.go, very basic too :

package main

import (
        tc "test/proto/test"
        "context"
        "fmt"
        "log"
        "net"

        grpc "google.golang.org/grpc"
        codes "google.golang.org/grpc/codes"
)

func main() {
        err := StartServer("tcp", "127.0.0.1:50051")
        if err != nil {
                fmt.Printf("Error!! %s", err)
        }
}

type Server struct {
        tc.UnimplementedTesterServer
}

func (s *Server) Test(ctx context.Context, in *tc.Request) (*tc.Reply, error) {
        return &tc.Reply{Message: ""}, nil
}

func StartServer(protocol string, port string) error {
        lis, err := net.Listen(protocol, port)
        if err != nil {
                fmt.Printf("failed to listen: %v", err)
        }
        s := grpc.NewServer()
        tc.RegisterTesterServer(s, &Server{})

        error := s.Serve(lis)

        if error != nil {
                fmt.Printf("failed to serve: %v", error)
                return error
        }

        return nil
}

Finally, I try to compile my proto files :

$ protoc --proto_path=.:$GOPATH/src --go_out=plugins=grpc:. proto/*/*.proto

And I systematically have the following error :

proto/test/test.proto:5:1: Import "github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis/google/api/annotations.proto" was not found or had errors.

When I see files get by go get ..., they are placed under $GOPATH/pkg/mod/

For example the googleapis' annotations.proto file is under : $GOPATH/pkg/mod/github.com/grpc-ecosystem/[email protected]/third_party/googleapis/google/api/annotations.proto

Maybe is it the cause?

Solution

Mixing up your protobuf commands and your go commands is making this more complicated than it needs to be. Just focus on the protobuf to handle the error.

You are importing "google/api/annotations.proto"

Your proto_path is --proto_path=.:$GOPATH/src

So that means that when you execute protoc you should have the file located at ./google/api/annotations.proto or $GOPATH/src/google/api/annotations.proto